1. Field of the Invention
The present invention relates to a differential feedback amplifier circuit, and more particularly, to a differential feedback amplifier circuit with cross coupled capacitors.
2. Description of the Related Art
Along with the wireless communication technology development, various wireless communication standards for different environments are continuously presented to the market, such as WCDMA (Wideband Code-Division Multiple Access), WLAN (Wireless Local-Area Network), HIPERLAN (High Performance Radio Local-Area Network), UWB (Ultra-wideband), and DVB (Digital Video Broadcast), . . . etc. Among various wireless communication standards, the quality of the wireless receiver used as the RF front-end is a major factor that impacts the communication quality. Therefore, it is a common objective of the communication industry to develop a differential feedback amplifier circuit which provides high circuit gain and bandwidth and advantages of low noise, low power consumption, better linearity, and a small Integrated Circuit layout.
FIG. 1 schematically shows a broadband low-noise differential amplifier for UWB (Ultra-wideband) standard based on the thesis of “A broadband low-noise front-end amplifier for ultra wideband in 0.13 μm CMOS” issued by Gharpurey, R. in Solid-State Circuits, IEEE Journal of Volume 40, Issue 9, September 2005 pp. 1983-1986. The circuit shown in FIG. 1 has a bandwidth range of 2 GHz˜5.2 GHz, which is not appropriate for the DVB (Digital Video Broadcast) standard.
FIG. 2 schematically shows a broadband low-noise differential amplifier for multistandard based on the thesis of “A new CMOS Wideband RF Front-End For Multistandard Low-IF Wireless Receivers” issued by Md. Mahbub Reja, Ahmed Allam and I. M. Filanovsky in Circuits and Systems, 2005. ISCAS 2005. pp. 2120-2123 Vol. 3. The circuit shown in FIG. 2 has a bandwidth range of 900 MHz˜3.5 GHz, which is not appropriate for the DVB (Digital Video Broadcast) standard, either.
Therefore, the major topic of the field is to develop a differential feedback amplifier circuit, which complies with the DVB (Digital Video Broadcast) standard, fulfills the circuit gain and bandwidth requirements, and has the advantages of low noise, low power consumption, better linearity, and a small Integrated Circuit layout.